The cell cortex is essential to maintain animal cell shape, and contractile forces generated within it by nonmuscle myosin II (NMY-2) drive cellular morphogenetic processes such as cytokinesis. The role of actin cross-linking proteins in cortical dynamics is still incompletely understood. Here, we show that the evolutionarily conserved actin bundling/cross-linking protein plastin is instrumental for the generation of potent cortical actomyosin contractility in the Caenorhabditis elegans zygote. PLST-1 was enriched in contractile structures and was required for effective coalescence of NMY-2 filaments into large contractile foci and for long-range coordinated contractility in the cortex. In the absence of PLST-1, polarization was compromised, cytokinesis was delayed or failed, and 50% of embryos died during development. Moreover, mathematical modeling showed that an optimal amount of bundling agents enhanced the ability of a network to contract. We propose that by increasing the connectivity of the F-actin meshwork, plastin enables the cortex to generate stronger and more coordinated forces to accomplish cellular morphogenesis.
License type:
http://creativecommons.org/licenses/by-nc-sa/4.0/
Funding Info:
This work was supported by the National Research Foundation
Singapore under its NRF fellowship (NRF-RF2009-RF001-074)
awarded to R. Zaidel-Bar and by the Ministry of Education–Singapore
(Tier 2 grants MOE2015-T2-1-045 and MOE2015-T2-1-116)
awarded to R. Zaidel-Bar and Y. Toyama, respectively